PABX and KEY telephone systems

1. KEY TELEPHONE SYSTEM
AND PABX SYSTEM
CUSTOMER PREMISES TELECOMMUNICATION, NETWORK
EQUIPMENT’S INSTALLATION, CONFIGURATION AND MAINTENANCE
M11
V S Imbulpitiya
BSc (electronic and automation
technology(Colombo Uni),
NDES(electrical/electronic)
Instructor (Electronic)
Department of technical education and
training

2. KEY TELEPHONE SYSTEM
• A Key Telephone System (KTS) is the traditional phone
system having phones with multiple keys/buttons and lights
that indicate which line(s) are in use at any given time and
typically have one attendant phone or separate box that acts
as controller for a limited number of lines and extensions.
• A key telephone system is in the same category as a PBX
(private branch exchange). You will often see equipment
categorized as PBX/Key. Key telephone systems rely on the
telephone company switching equipment, while PBX systems
rely on a central control unit located at the business-
customer’s location.

3. KEY TELEPHONE SYSTEM
• Smaller ,cheaper but less flexible alternate to a privaet
branch exchange telephone system(PABX)
• A KTS is equipped with several buttons that allow a caller to
directly select outgoing lines or incoming calls, and use
intercom and conference facilities.
• Unlike in a PBX, a user does not have to dial '9' to access an
outgoing line, but the incoming calls are not automatically
routed to the called party.
• KTS are user-installable and allow handling of multiple lines
without paying a surcharge to the telephone company.
However, the hunt-group service cannot be provided on
them.

4. KEY TELEPHONE SYSTEM AND PABX SYSTEM
Key systems can
based on 3 main
architectures:
•Electromechanical
shared-control
•Electronic shared-
control
•Hybrid key
telephone system

5. KEY TELEPHONE SYSTEM
On a typical key telephone system, each incoming central
office line appears on a separate button on every key
telephone set that is allowed to make or receive calls on
that line.
A visual indicator, such as a small incandescent lamp or
light-emitting diode, allows the user to tell if the line is in
use. The same lamp flashes at a certain rate when an
incoming call is ringing on the line, and flashes at a
different rate when a call is on hold.
The number of lines that appear on every key telephone
set varies with the capacity of buttons on each set. Such

6. PABX(PBX) SYSTEM
What is PBX
• Private branch exchange (PBX) makes connections among internal
telephones of an organization and also connects them to the
public switched telephone network (PSTN) via trunk lines. Since
equipment including telephones, fax machines, modems, and
more are also incorporated, any end points of the system is
referred to as "extension". It controls all the incoming and
outgoing calls and connects outside callings with inside
extensions and internal extensions with each other. There are
fewer outside lines than extensions because all extensions will
probably be not used at once.
• The main advantages of PBX are the automated features,
flexibility and easy setup. PBX can be customized, can have
simple or sophisticated features, and individual lines may have
different functions on them. Deriving from their architecture,

7. PABX SYSTEM
• PBX is differentiated from Key systems in line
selection. In case of key systems users need to select
outgoing lines manually, while PBX selects outgoing
lines automatically. PBX also employs a dial plan that
is usually a single digit code. Users need to dial an
escape code to be connected to an outside line. This
code then is followed by an external number.
• Due to the growing popularity of PBXs, they have been
further developed. In this way services like call
forwarding and extension dialing has been included.
Later, because of the massive growth of data network
and packet switching needs, VoIP PBX or IP PBX has
been developed that allows packet switching over the

8. PABX SYSTEM

9. COMPONENTS OF PABX SYSTEM
• Internal switching network.
• Microcontrollers and microcomputer for arbitrary data
processing for control and the logic.
• Logic cards, switching and control cards, power cards and
related devices to
facilitate operation.
• Stations or telephone sets, sometimes called lines.
• External Telco trunks that deliver signals to and from the PABX.
• Console or switchboard allows the operator to control incoming
calls.

10. BEFORE FIXING PABX SYSTEM:
The area should be well protected from rain.
• It should be an air conditioned area.
• Power back, power connections and earthing issues must be
checked and verified.
• Dust free room is necessary.
• Connection diagram mentioning the places to fix PABX
machines and computer
• for programming.
• Wiring must be planned having the future enhancements in
mind.

11. AFTER FIXING A PABX SYSTEM:
• The number plan and the list of extension lines should be
documented and stored safely.
• Every extension should be numbered based on MDF (Main
Distribution Frame) and stored for future reference.
• According to the saved document the extension phones should
be configured. The configuration should be done based on the
guidance of the service providers or by referring the user
manual.
• After configuring the extension lines, each line should be
checked and verified.

12. KEY TELEPHONE SYSTEM AND PABX SYSTEM
PBX functions
Establishing connections (circuits) between the
telephone sets of two users (e.g. mapping a dialed
number to a physical phone, ensuring the phone
isn't already busy)
 Maintaining such connections as long as the users
require them (i.e. channeling voice signals between
the users)
Disconnecting those connections as per the user's
requirement

13. KEY TELEPHONE SYSTEM AND PABX SYSTEM
Calling features:
Auto attendant
Auto dialing
Automatic call distributor
Automated directory services (where callers
can be routed to a given employee by
keying or speaking the letters of the
employee's name)
Automatic ring back
Call accounting
Call blocking
Call park
 Call pick-up
Call transfer
Voice message broadcasting
 Welcome Message
 Call forwarding on busy or absence
 Call waiting
 Camp-on
 Conference call
 Custom greetings
 Customized Abbreviated dialing (Speed
Dialing)
 Busy Override
 Direct Inward Dialing
 Do not disturb (DND)
 Interactive voice response
 Music on hold
 Night service
 Public address voice paging
 Shared message boxes (where a department
can have a shared voicemail box)
 Voice mail

14. KEY TELEPHONE SYSTEM AND PABX SYSTEM
Calling features:
Direct Inward System Access (DISA) (the ability to access internal
features from
an outside telephone line)
Do not disturb (DND)
 Follow-me, also known as find-me: Determines the routing of
incoming calls. The
exchange is configured with a list of numbers for a person. When a
call is
received for that person, the exchange routes it to each number on
the list in turn
until either the call is answered or the list is exhausted (at which

15. IP PABX SYSTEM
What is IP PBX (IP-PBX, IP/PBX or IPPBX)?
• P PBX is a business telephone system developed to transfer voice or video
over a data network. IP stands for Internet Protocol, PBX stands for Private
Branch Exchange. IP PBX is a private system that switches calls between
VoIP users on local lines and these users can also share some external
phone lines. IP PBX systems are also able to interoperate with Public
Switched Telephone Network (PSTN) and switches calls between a VoIP
user and a traditional phone user or between two traditional phone users.
• This functionality enables businesses to use their managed intranet to
reduce long distance costs and benefit from a single network that is used
for voice and data transfer providing greater mobility and cost
effectiveness, while reduce redundancy. Since IP PBX deploys converged
data and voice networks, Internet access, VoIP communications and
traditional telephone communications are available using a single line to

16. IP PABX SYSTEM
What is IP PBX (IP-PBX, IP/PBX or IPPBX)?
• The other benefit of IP PBXs is that it is quite cost effective and
easy to add additional functionality to the system. In this way
conferencing, XML-RPC control of live calls, Interactive voice
response (IVR), TTS/ASR (text to speech/automatic speech
recognition), Public switched telephone network (PSTN)
interconnection ability supporting both analogue and digital
circuits, Voice over IP protocols including SIP, etc can be
included.
• On Figure you can see an IP PBX connection architecture. It
demonstrates that soft phones and VoIP phones can connect to
the IP PBX system to make calls. If you would like to call
another VoIP phone user you can do so over the Internet. If you

17. KEY TELEPHONE SYSTEM AND PABX SYSTEM

18. Thank you
V S Imbulpitiya
BSc (electronic and automation
technology(Colombo Uni),
NDES(electrical/electronic)
Instructor (Electronic)
Department of technical education
and training